1. Field of the Invention
The present invention relates to aquaculture devices, and particularly to a fish culturing system utilizing air to aerate and circulate water and power the system, as well as maximize fish population density and aquaculture for a given space.
2. Description of the Related Art
As more and more people are consuming fish to achieve health benefits, demand for commercially raised fish has increased. To meet this demand, a fish culturing system that is inexpensive and efficient to use is needed. Additionally, it is beneficial to have such a system indoors, rather than exposed to the elements.
To meet this increased demand and minimize space needed for the operation, the number of fish grown in a certain volume of water must be maximized. In increasing the number of fish per certain volume, several concerns must be addressed. Increased fish population means increased demand for oxygen from the same volume of water. Aeration of the water helps increase levels of dissolved oxygen for use by fish, thereby allowing an increase in the fish population. Of course increased population means increased feeding and increased waste production. Excess food and waste in the water begin to break down producing ammonia, which is toxic to fish even at low levels of concentration. Frequent water changes help alleviate this problem, but are costly and wasteful of the natural resource. Reuse and recycling of the water is therefore not only desirable, but environmentally and economically mandated. Water in the tank contains toxic levels of ammonia and suspended solids from fish wastes and food residues. Thus, filters have been developed that remove suspended solids from the water by physical means, and convert deadly ammonia to harmless nitrate by biological filtration, before returning water back to the tank.
Such filtering systems generally pump water from a rearing tank through an area having increased surface area harboring bacteria which convert the deadly ammonia to harmless nitrate, while a filter bed traps suspended solids before returning the water to the tank.
An example of such a fish culturing system is disclosed in U.S. Pat. No. 6,065,430, hereinafter referred to as '430 patent, issued to Richard L. Sheriff on May 23, 2000. The fish culturing system therein uses pressurized or compressed air to facilitate all the pumping required to recirculate the water through a culture tank, where the fish being grown reside, and a separate purifying unit coupled to the culture tank to clean the water of waste material and ammonia. This can substantially reduce energy consumption and costs compared to the typical electric water pumps utilized in most conventional systems. In addition to the motive force for moving water, the air also provides all the aeration for the fish being grown and the nitrifying bacteria in the filter bed. Also, the fish culturing system in the '430 patent includes a central waste overflow manifold suspended along the length of the culture tank directing waste that can float near the surface of the water in the culture tank to the purifying unit.
However, with fish culturing systems, space can be a concern with respect to production and maximizing yield of the farm grown fish. For a given amount of space, a purifying unit of a fish culturing system can present a structure occupying space that can potentially be used for a larger culture tank. The purifying unit can also very labor intensive to maintain because the filters must be cleaned frequently.
Thus, it would be desirable to have a fish culture system that can draw waste from the culture tank, recycles and recirculates water, while aerating and nitrifying the water, efficiently and economically. Thus, a fish culturing system addressing the aforementioned problems is desired.